Structure of the vitreous body observations by means of the phase-contrast microscope.

THE problem of the structure of the vitreous body has long been debated. According to Duke-Elder (1930), the argument is beset with difficulties over which anatomists have disputed from the earliest times, largely because of the difficulties involved in the interpretation of their observations. Many studies have been undertaken with the microscope on fixed specimens, with the ultramicroscope on fresh vitreous, and with the slit-lamp in the living eye. Most workers, including Baurmann (1923), Comberg (1925), Heesch (1926), Redslob and Reiss (1928), and Duke-Elder (1930), on the basis of their observations or from chemical studies, reached the conclusion that fresh vitreous body is to be considered a colloid in the form of a gel and is completely free from microscopical structures as these are usually understood. Recently, however, the problem has again attracted interest, and several investigators whose findings do not always agree in detail, have maintained that the vitreous body has a fibrous structure. By means of the phasecontrast and electron microscope, Schwarz and Schuchardt (1950), Schwarz (1951), Bembridge, Crawford, and Pirie (1952), and Grignolo (1952), succeeded in demonstrating some fibrous elements in the fresh vitreous of several species; these varied in shape, size, and pattern according to the part of the vitreous body from which they were derived. The present research was started with the intention of studying the vitreous in both normal and pathological conditions in animals and human beings. When the preliminary results had been obtained, however, it was thought sufficient to limit the investigation to the normal vitreous body of animals, since fresh specimens invariably failed to reveal a true fibrous structure.